Vp/Vs Ratio Variations and Earthquake Prediction in Aswan, Egypt
Mosbeh El-Zeen Megahed;
Abstract
Earthquakes have killed 2.7 million people during the period from
1900 to 1976. Scientists are currently looking for ways to predict earthquakes, so lives could be saved. This study generally reviews one method of earthquake prediction: the method of Vp/Vs ratio for earthquake prediction.
Aswan region is selected for this study, because it is characterized by the presence of the Aswan seismic network, which records the seismic data very well and the construction of the largest man-made important reservoir in the world, that is characterized by its deviation from the classical reservoirs.
For this study, about 1283 local earthquakes, occurring around
Kalabsha fault system, recorded between January 1988 and December
1998, were playbacked from the Fm magnetic tapes. These events were chosen from the three active zones in Aswan area (GMRZ, EGMRZ and KRMZ).
Several important questions still remain to be answered before using the velocity changes as a useful predictive element of earthquakes in Aswan area: do detectable velocity changes precede earthquakes?, if
so, do these changes precede all types of earthquakes?. In cases, where these changes are observed, what is the size of the anomalous area?, and in these cases, can the precursor time interval be related to the earthquake magnitude by a more or less universal relation?.
However, the most important result of this study is that, a valid measure of the velocity ratio in the source medium can be obtained from the Wadati diagram. The difficulties of applying a technique, that depends on the reliable detection of both the P and S phases from small events in Aswan area were considered. The Vp!Vs technique was used successfully for the first time to predict the approximate magnitude, the time and the place of occurrence of the earthquakes in Aswan area. An important aspect of the prediction was that, the magnitude and the time of occurrence of the earthquake were determined prior to the return of Vp / Vs to normal.
1900 to 1976. Scientists are currently looking for ways to predict earthquakes, so lives could be saved. This study generally reviews one method of earthquake prediction: the method of Vp/Vs ratio for earthquake prediction.
Aswan region is selected for this study, because it is characterized by the presence of the Aswan seismic network, which records the seismic data very well and the construction of the largest man-made important reservoir in the world, that is characterized by its deviation from the classical reservoirs.
For this study, about 1283 local earthquakes, occurring around
Kalabsha fault system, recorded between January 1988 and December
1998, were playbacked from the Fm magnetic tapes. These events were chosen from the three active zones in Aswan area (GMRZ, EGMRZ and KRMZ).
Several important questions still remain to be answered before using the velocity changes as a useful predictive element of earthquakes in Aswan area: do detectable velocity changes precede earthquakes?, if
so, do these changes precede all types of earthquakes?. In cases, where these changes are observed, what is the size of the anomalous area?, and in these cases, can the precursor time interval be related to the earthquake magnitude by a more or less universal relation?.
However, the most important result of this study is that, a valid measure of the velocity ratio in the source medium can be obtained from the Wadati diagram. The difficulties of applying a technique, that depends on the reliable detection of both the P and S phases from small events in Aswan area were considered. The Vp!Vs technique was used successfully for the first time to predict the approximate magnitude, the time and the place of occurrence of the earthquakes in Aswan area. An important aspect of the prediction was that, the magnitude and the time of occurrence of the earthquake were determined prior to the return of Vp / Vs to normal.
Other data
| Title | Vp/Vs Ratio Variations and Earthquake Prediction in Aswan, Egypt | Other Titles | تغيرات نسبه سرعات الموجه الطوليه إلى الموجهالمستعرضه والتنبؤ بالزلازل فى اسوان ، مصر | Authors | Mosbeh El-Zeen Megahed | Issue Date | 2000 |
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